It took only 30 minutes for him to gather enough support. Many celebrities, including famous entrepreneur Takafumi Horie, joined in.

Mr. Ieiri, one of the youngest Tokyo governor candidates ever, hadn’t been involved in politics before his December tweet, but he’s drawn a following online over the years, especially after he became the youngest manager to list his company on JASDAQ when he was 29.

While running several internet-service companies and restaurants, Mr. Ieiri has also been active on Twitter, occasionally asking his followers to donate money to various causes. Most recently, he helped a mother to raise the cost of a delivery through twitter — “croud birthing funding,” he called it.

Mr. Ieiri’s campaign sharply contrasts with Japan’s traditional election scene. Mr. Ieiri didn’t have any policy agendas when announcing his decision to run, he raised ¥7.2 million via croud-funding to pay for his campaign costs, and his around-the-clock headquarters often gets most lively at night. The office is equipped with a live-streaming camera and a DJ booth, and on one recent occasion, a supporter was spotted sleeping on a couch at 11 a.m., with a leftover pot noodles and paper coffee cups from the night before nearby.

Mr. Ieiri said he has long been worried about weakening community networks and intergenerational bonds in the world’s third-largest economy, and through his experience of running shared-houses across the nation, he said he felt the need to tap into the political arena at some point.

He realized there were some limits to what the private sector could do in fostering a sense of community, especially in the wake of the 2011 earthquake and tsunami. The government could also help pick up the slack in areas such as community planning.

Supporters gather to help Mr. Ieiri’s campaign.

“I want to help creating a place to belong for everyone, and it’s something that the private sector cannot do alone, so I wanted to start making changes from the political side,” Mr. Ieiri, a high-school dropout and father of two, said.

He said another campaign goal is to set an example that politics can be accessible to anyone, especially young people. According to a survey by the Tokyo Metropolitan Government, the city is relatively young, with people between the ages of 20 and 49 accounting for 45% of the total population. Those aged 50 and higher make up 40% of the city’s population. Still, the voting rate of the younger population during the last Tokyo gubernatorial election was low, with only half voting, as opposed to 72% for the older population.

“I was feeling politics is just for some and has nothing to do with me because I thought the circle is something scary, something you can get arrested by, or even be stabbed by,” Mr. Ieiri said. “But now I’m on, and it’s actually super fun.”

Instead of coming up with campaign platforms by himself, Mr. Ieiri asks supporters to suggest ideas through Twitter—a tactic that has drawn criticism from some people as lacking initiative. “Our doctrine,” Mr. Ieiri says, is being compiled in real-time on his website, using Google Docs.

“I thought it’s not right to dump specific policy agendas on the people, by speaking from somewhere high,” Mr. Ieiri said. “Other candidates are using the Internet just as another form of television that is only one-way. But what we can do and should do with the technology is interaction.”

Public polls by major Japanese media suggest that Mr. Ieiri’s chances of winning are slim. Asked if his ultimate campaign intention is to win, he said, “yes” – though he paused for a few seconds and had a quick chat with his public relations chief next to him before he responded.

His supporters also believe he has a shot of winning, but many say his campaign alone is already history-making.

“Until now, to run for election is something for special, selected and rich people,” said Yuya Muto, a 35-year-old freelance photographer. “But Mr. Ieiri proved that everyone motivated can do it, if they successfully deliver their message to raise funds and support via online. It drastically made the thing easier.”

Mr. Ieiri said if he doesn’t get a seat, he plans to pass on “our doctrine,” to a winner, because “that’s what people want for politics.”

A 360-degree photo of Mr. Ieiri’s campaign office equipped with a live-streaming camera and a DJ booth

About Japan Real Time

Japan Real Time is a newsy, concise guide to what works, what doesn’t and why in the one-time poster child for Asian development, as it struggles to keep pace with faster-growing neighbors while competing with Europe for Michelin-rated restaurants. Drawing on the expertise of The Wall Street Journal and Dow Jones Newswires, the site provides an inside track on business, politics and lifestyle in Japan as it comes to terms with being overtaken by China as the world’s second-biggest economy. You can contact the editors at japanrealtime@wsj.com